The Hydrogen Envelope and Supercritical Mantle of Sub-Neptune HD 110067 c
In the quiet stellar field of the constellation Coma Berenices, roughly 100 light-years from Earth, orbits an extraordinary planetary system anchored by HD 110067, a bright K-type orange dwarf star . Among the six synchronized sub-Neptunes inhabiting this system, HD 110067 c stands as a textbook archetype of the sub-Neptune planetary class—worlds larger than Earth but smaller than Neptune that possess no direct analog in our own solar system. Characterized by a bloated, volatile-rich gas envelope overlying a high-pressure interior, HD 110067 c offers planetary scientists an unfiltered window into the accretion physics and atmospheric conservation of sub-Neptune worlds. Discovered through high-precision transit photometry by space-based observatories, HD 110067 c orbits its host star at a distance of approximately 0.09 astronomical units , completing a full revolution every 13.6 days. With a radius roughly 2.38 times that of Earth and a bulk mass measuring approximately 5.3 ...